Today's KNOWLEDGE Share:FOUNTAIN FLOW AND FREEZING

Today's KNOWLEDGE Share:

FOUNTAIN FLOW AND FREEZING:

I often get questions in my seminars about molecular orientation in molded specimens.

People often get a bit confused about the layers that could possibly show some degree of molecular orientation, potentially observed as birefringence for transparent grades.

- The very skin is coming directly from the fountain flow and freezing, so it is not very oriented at all since it never experienced much flow in the main direction.

- The "frozen skin" below it is extremely oriented since, by definition, it freezes UNDER FLOW. As a result it is very oriented, almost regardless of the polymer relaxation time / molecular weight.

- Other layers below, approaching the center line can show orientation induced during the second stage of the molding process, the packing phase. This flow stress is active at later times, thus acting on deeper layers.

- Although thick parts should show little orientation below the frozen skin, high molecular weight materials could still show significant orientation if their relaxation time exceeds the overall cooling time of the specimen. Try molding a blow-molding grade and see for yourself !

- Strictly speaking, the very center line should not show orientation since the shear-rate and shear-stresses are zero at all times during the process.

A quick test to assess the degree of average orientation (which really works perfectly for opaque crystalline polymers) is to examine the degree of (post-)shrinkage in the flow direction when annealing the specimen at the appropriate temperature (just below Tg for amorphous, just below Tm essentially for semi-crystalline).

Orientation is not strictly speaking a "residual stress" given the weakness of the entropic force at play. Upon reheating or softening with a solvent (PVC and acetone for instance reveal flow induced orientation), such tiny force can produce this significant post-shrinkage.

Source:VITO LEO

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#plastics #injectionmolding #amorphous #semicrystalline #relaxationtime #molecularorientation #freezing #orientation #flow

Today's KNOWLEDGE Share:Bioluminescent:

Today's KNOWLEDGE Share:

Bioluminescent:
My passion for innovation and the sportswear industry has led me to envision a near future where bioluminescence is applied to sportswear fabrics.

Inspired by this idea, I have created with the help of AI a night-time running jacket that ensures visibility and protection when darkness falls.

BioGlow™
Redefining night-time running with our new revolutionary bioluminescent running jacket
Introducing the ultimate companion for night-time runners. Our revolutionary running jacket is designed to elevate your safety and style.

Embrace the power of bioluminescence with our innovative application that illuminates the jacket, ensuring visibility and protection when darkness falls.
This cutting-edge technology uses natural light-emitting organisms to create a captivating glow, making you instantly recognizable to drivers even in the darkest of nights. Crafted with precision and performance in mind, our running jacket combines waterproof materials and breathable fabrics, allowing you to conquer any weather conditions without compromising on comfort.
With its sleek and sporty design, this jacket embodies both functionality and fashion, empowering you to shine bright as you pursue your running goals. Stay safe, stay visible, and enjoy running!

Currently, bioluminescent clothing is not widely available on the market.
However, scientists are conducting research to harness bioluminescence for technological applications, including clothing. There have been some demonstrations of prototype garments that utilize bioluminescent materials, such as fabrics impregnated with fluorescent proteins derived from jellyfish or genetically modified bacteria. These materials can be activated by a source of energy, such as pressure or movement, to produce a faint light.

Despite promising discoveries in research, bioluminescent clothing is not yet a practical or widespread option for the average consumer. There are several technical challenges to overcome, such as the long-term stability of bioluminescent materials, their durability, and safety for human use. Additionally, there are ethical considerations regarding the use of living or engineered organisms for the production of bioluminescent materials.

However, with further developments in research and technology, it may be possible to see the emergence of bioluminescent clothing in the future. It could lead to unique and fascinating creations that naturally light up, offering new creative possibilities in the fashion industry.

Source:Ignacio Valentini
Visit MY BLOG https://lnkd.in/fcSeK9e

#innovation #creative #textileindustry #fashiontrends  #fashion #bioluminiscence #sportswear #fashionindustry #research #conceptdesign #clothing 

Today's KNOWLEDGE Share:SODIUM-ION BATTERY INDUSTRY

Today's KNOWLEDGE Share:

SODIUM-ION BATTERY INDUSTRY

The working principle of a sodium-ion battery is similar to that of the lithium-ion battery following an intercalation-based “rocking chair” mechanism, whereby the embedding (intercalation) and stripping (deintercalation) process of sodium-ion between positive (cathode) and negative (anode) electrodes, which are parted by the separator soaked in electrolyte, realises charge and discharge.

In terms of product performance, sodium-ion batteries advantages include good safety, rate performance, and low temperature performance, but have the disadvantages of poor cycle life and its energy density is comparable to only that of conventional lithium iron phosphate batteries.

Due to the comparable energy density, excellent rate performance and significant cost advantage of sodium-ion batteries, they are considered cost-effective and will be applied to large-scale energy storage systems, two-wheeler electric vehicles and low-speed electric vehicles and are expected to complement and eventually replace lithium-ion batteries in the future. Large-scale energy storage systems mainly include wind power plants, solar power plants and household energy storage systems while low-speed electric vehicles mainly include logistics vehicles, agricultural vehicles, electric vehicles, electric buses and electric boats.

Source"Brendan Jephcott

Visit MY BLOG http://polymerguru.blogspot.com

#evbatteries #sodiumionbattery #ev

Today's KNOWLEDGE share:Wind turbine blade damage:

Today's KNOWLEDGE share:

Wind turbine blade damage:

As we all know, erosion can be a huge problem when dealing with wind turbine blades... The thing is, generally, wind turbines are so far from us that we almost never see how erosion can affect them! Unless... You get quite close to it! 

To combat leading edge erosion, wind turbine operators employ maintenance and repair techniques that ensure the blades maintain optimal performance. When signs of erosion become apparent, proactive measures are taken to restore the blades to their original condition and preserve their efficiency. 

However, in this case, it seems that no precautions were taken... I mean, just look at how bad it got! 

In this case, we can say that shit is slowly, but constantly hitting the ''fan''.

Guess a more durable leading-edge protection material would be handy! 

Source: Alexsandro Pedro da Silva - GWO/ #managingcomposites

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#composites #windblade #windenergy #windturbine #erosion #maintenance

Today's KNOWLEDGE Share:Mold Coatings:

Today's KNOWLEDGE Share:

Mold Coatings:

If you browse through the documentation of mold coating suppliers (PVD, WS2, others) they all claim better flow (i.e. lower pressure to fill) after coating the mold with just a few microns of their coating (typically a metal oxide, salt, or some other complex).

These layers do impart lubricity indeed, which is great to help ejection of the molded part.

But in Injection Molding there is no slip against the wall. Actually if/when you get some, you invariably end up with a surface defect !

So improved lubricity, as claimed by suppliers, DOES NOT explain better flow.

What is most probably happening is that the added layer, which is not "metallic" has always a lower Thermal Effusivity.

Effusivity is the material property that controls interfacial temperature.

So what we really have here is a slightly thinner frozen skin resulting from a somewhat higher interfacial temperature between plastic and coated steel. In a flat flow, effective available thickness for flow has a quadratic effect on pressure drop. For a runner/gate (cylinder) it is even a cubic dependence.

So the smallest reduction in the frozen layer, especially for thin cavities, can immediately explain the observed 5-10 % decrease in pressure drop (or, conversely, increase in flow length).

Source:VITO LEO

Visit MY BLOG http://polymerguru.blogspot.com

#plastics #injectionmolding #runner #gate #moldflow #coatings #lubrication #polymerscience #moldfilling #frozen #lowcoeffient

CAI Performance Additives Unveils Epoxy Chain Extender for Virgin & Recycled Materials

CAI Performance Additives announces the launch of the latest product, ST-CE37, a polymeric epoxy functional chain extender for both virgin and recycled materials needing help to meet performance and process requirements.

Improving Viscosity Characteristics of Polymers:

This innovative additive significantly improves viscosity characteristics, mechanical properties, and inhibits the hydrolysis of polymers such as PA, PET and other polycondensation resins.

ST-CE37 chemistry beats competitors given its innovative reactive side chain, so the chain extension is much easier for the host polymers to ‘find’ during compounding.

The commitment to provide innovative solutions for the plastics industry, and the introduction of ST-CE37 is just one example of their dedication to deliver superior products that meet the evolving needs of the customers.

Source: CAI Performance Additives/Polymer-additives.specialchem.com

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#polymers #plasticsindustry #specialtychemicals #epoxychainextender #recycledplastic

Today's KNOWLEDGE Share: EV BATTERY:

Today's KNOWLEDGE Share:

EV BATTERY:

Although lithium-ion batteries have high energy density and cycle life, the cost and safety of the batteries limit their widespread use in this field. Sodium-ion batteries not only have high safety and cycle life, but also have obvious advantages over lead-acid batteries in terms of energy density, making them a good alternative to lead-acid batteries in the field of low-speed electric vehicles. In the low-speed vehicle market, sodium-ion batteries are cost-effective and competitive. The low-speed vehicle market does not require high energy density and the performance of sodium-ion batteries is sufficient to meet the needs of low-speed electric vehicles.

After determining the standard for miniature low-speed pure electric passenger vehicles, the majority of car companies have clear goals, and they have tried to slice the cake in the low-speed electric market and launched low-priced A00-class electric vehicles. Beginning in July 2020, China has organised new energy vehicles to the countryside for three consecutive years. Among them, A-class and A00-class pure electric vehicles have become the main models for going to the countryside.

Low-speed vehicles and A00-class electric vehicles have low cruising range and low requirements on the energy density of power batteries. In 2018, Zhongke Haina launched the world's first low-speed electric vehicle driven by a sodium-ion battery (72V, 80Ah), opening up the world's first low-speed electric vehicle driven by sodium-ion batteries.

At present, there is a strong demand for short-distance transportation such as picking up and dropping off students to and from school and short-distance shopping in urban areas. With the acceleration of urbanisation in rural areas, road transportation facilities are gradually improving, and the demand for motorised travel is increasing. Against the background of stricter regulations and rising cost of lithium-ion batteries, sodium-ion batteries are expected to develop rapidly in the field of low-speed vehicles and A00-class vehicles.

Source:Brendan Jephcott

Visit MY BLOG http://polymerguru.blogspot.com

#ev #evbatteries #evchargers #lithiumionbatteries #sodiumionbattheries

#electricvehicles #alternativeenergy #carbonneutral #batteries #energy #safety #travel #transportation